Summary

The Joint Research Project „Multidimensional reflectometry for industry“ is a collaboration between National Metrology Institutes, partners from Industry and the research Community in Europe.

The aim of the project is to validate reliable optical measurements with traceability to the SI-system to describe the overall macroscopic appearances of modern surfaces.

Planned work

In particular, the project deals with the Goniochromatism, Gloss and Fluorescence properties of dedicated artefacts, which are investigated in the three main workpackages (WP1, WP2 and WP3).

Workpackage 4 addresses the Modelling and Data Analysis in order to give an irreducible set of calibration schemes and handling methods. Workpackage 5 studies the Human Visual Perception, in order to provide physical scales that correlate with the visual sensation.

Project objectives

The project xDReflect aims to improve primary metrology in the field of material characterisation, in order to provide new measurement protocols and new standard artefacts that will permit industry to control the visual appearance of the surfaces they produce. To be easily exploitable, these measurementsmust correlate with the human visual sensation.

From a metrological point of view, in this field, the relevant quantity is the Bidirectional Reflectance Distribution Function (BRDF), that is the ratio of the radiance in one given direction to the irradiance coming from another direction, at a given wavelength. The BRDF is measured with a goniospectrophotometer and provides a full characterisation of the light reflected by the sample. Our objectives therefore relate to the measurement and understanding of the BRDF.

The main objectives of the project are:

Improvement of primary goniospectrophotometers in order to improve BRDF measurement and reduce the measurement uncertainty.

Development of models for data compression, data representation and data handling of BRDF measurement.

Understanding of correlation between the visual appearance and the BRDF.

Development of standard procedures and transfer artefacts in order to provide applied metrology for visual appearance attributes.

Impact

The work performed within this project will drastically enhance the measurement capabilities of the European NMIs in the field of gonioreflectometry dedicated to the characterization of the appearance of the materials. Measurement uncertainties and measurement time will be reduced; traceability for commercial products in the field of appearance will not only be assured, but also strengthened. The procedures evolving from this project will enter the market and especially support quality control in different production fields, where appearance and surface quality and structure is important. Scientifically, the interaction between incoming light and appearance of the surface will be much better understood.